The present invention generally relates to a communication apparatus, such as a facsimile machine, and more particularly to a communication apparatus which has a remote control operation mode activated by a password which is supplied from a remote terminal.
Recently, the number of functions provided on a telephone has been increasing, and a telephone having a remote control operation mode, in which respective functions can be controlled based on a predetermined DTMF (Dual Tone Multifrequency) signal transmitted from a remote telephone terminal, has been proposed.
Conventionally, these types of telephones are disclosed, for example, in Japanese Utility Model Laid Open Publication Nos.63-181043 and 63-185342.
In the former, a calling operation, an on-hook operation and an off-hook operation in a telephone can be activated based on a password represented by the DTMF signal supplied from a remote telephone terminal. In the latter, electrical appliances are remotely controlled based on a password represented by the DTMF signal which is transmitted via the telephone line.
The above remote control, which is activated based on the password, can be used in a facsimile machine having a telephone. For example, information stored in the facsimile can be read out by remote control. In this case, as the remote control is activated based on a password, unspecified users can be prevented from obtaining the information in the facsimile machine.
However, in the facsimile machine in which the remote control can be activated based on the password, by repeatedly trying different passwords, the correct password can be discovered. That is, it is difficult to keep the information in the facsimile machine having a remote control operation mode secret by only the password. Thus, the security of the facsimile having the remote control operation mode deteriorates.